nekdut Posted February 17, 2014 Report Share Posted February 17, 2014 Sorry in advance for the rant/vent. This was originally supposed to be a ride review of my original Madd 180, which some of you have been asking about. I've been waiting for decent coverage before trying this board out since it is pretty unique. We've had a had a terrible snowfall this year so it's taken some time. I finally got it out on Friday and the board blew my mind. It is truly a unique stick in the alpine snowboarding world. So, I used longer binding screws, checked and rechecked before riding, but my front binding completely sheared off of the board five runs into the day on Friday. I was hauling in a good heelside (lower Stump Alley for those who know, so you can get real speed there) and thankfully was able to get sliding my back quickly to avoid my rear leg/knee from getting thrashed from catching one-legged. I was able to collect myself gather up the yellow ering that popped off and get down to my car. Felt like some good bruising on my front knee and shin, but I was glad it wasn't any worse. Only after getting back to my car and unbooting, I noticed a little moistness on my knee and discovered a nice clean slice down to my kneecap. The board had a fresh PTC tune and most of you know how razor sharp that can be. My ski pants and under layer have perfectly straight and clean slices at the knee as well. I was able to drive myself to the hospital and get stitched up, with a little tendon damage underneath unfortunately. Now, I wanted to ask the group, how best to check if your binding attachment is truly sufficient? All four front screws had 3-4 turns of engagement and looked clean and tight. Is it just the fact classic Madd brass is softer and just gave way (particularly since these boards are getting upwards of 2 decades old)? The weird thing is that screwing back into the board still feels secure, but there's no way I am taking the board out as-is, after my visit to the ER. What are my options in making the inserts stronger as-is? Heli-coil? Or do I need to t-nut the thing to be sure? By the way, the classic 180 was phenomenal. I'm still thinking about it a few days later. It's surprisingly friendly, perhaps since this specific example spent a fair amount of time being thrashed on the world cup and has been softened a bit. It does not feel like the documented 22m elliptical sidecut, nor the 17.7m measured. It needs some speed, but once moving is pretty maneuverable, feeling more like a 13-16m radius VSR. One thing I felt (might be technique related) is that I did not complete full C-carves on this thing, it wanted to go down the fall line and just haul ass. I want to get back on this thing but am scared the binding issue will bite me again...... :( Quote Link to comment Share on other sites More sharing options...
Unicorn Poop Posted February 17, 2014 Report Share Posted February 17, 2014 SNow, I wanted to ask the group, how best to check if your binding attachment is truly sufficient? All four front screws had 3-4 turns of engagement and looked clean and tight. You generally want at least a diameter's worth of thread engagement. So, for a 6mm bolt, you want at least 6mm of engagement. The number of turns this is depends on the thread pitch. I believe the thread pitch on our screws are 1.0mm, so you'd actually need six turns. If the material is softer, such as brass, you'd want more engagement; depending on the type of brass alloy, it could be quite a bit more. That's just the engagement; the torque is probably quite a bit lower than you think- only seven foot pounds or so. But that's for steel. Since the inserts are brass, that could drop to between three and five foot pounds. If you were using the same screws you always use with that particular set of bindings on different boards, and were cranking down the screws as tight as you would on a board with steel inserts, there's a good chance that you overtorqued your screws. You could helicoil, assuming the OD of the insert is big enough to allow for this, both in diameter and integrity. If not, you could drill and tap for a larger bolt, since a larger bolt will require less engagement length and allow for a higher torque value. Or, replace the inserts all together. Quote Link to comment Share on other sites More sharing options...
Bordy Posted February 17, 2014 Report Share Posted February 17, 2014 Is it just the fact classic Madd brass is softer and just gave way (particularly since these boards are getting upwards of 2 decades old)? ( Yes. Plenty of threads discussing this issue in the past. Quote Link to comment Share on other sites More sharing options...
carvingchef Posted February 17, 2014 Report Share Posted February 17, 2014 You generally want at least a diameter's worth of thread engagement. So, for a 6mm bolt, you want at least 6mm of engagement. a larger bolt will require less engagement length i am a little confused, if the first quote is correct, than, shouldn't the larger bolt require a longer engagement length because the diameter of the larger bolt is bigger Quote Link to comment Share on other sites More sharing options...
Unicorn Poop Posted February 17, 2014 Report Share Posted February 17, 2014 (edited) i am a little confused, if the first quote is correct, than, shouldn't the larger bolt require a longer engagement length because the diameter of the larger bolt is bigger I apologize. That was confusing and I should have been more clear. I meant that if he tapped out the stripped insert for a larger bolt and retained the same thread engagement length as he currently has (or had), the larger screw would hold a higher load. All things being equal (load, material strength), a larger diameter fastener will hold the same load with less engagement length. Given that he was only able to get three turns (half of what is generally required) and that the insert is of a softer material, the same engagement length of three turns in a larger diameter fastener will be stronger. The statement that one diameter of thread engagement is a very general and broad reaching statement, but is a safe rule to adhere to when other factors are unknown. Edited February 17, 2014 by Unicorn Poop Quote Link to comment Share on other sites More sharing options...
lowrider Posted February 17, 2014 Report Share Posted February 17, 2014 I'm confused by your description "the binding sheared off the board" that description tells me the screw ends are still in the inserts with the heads sheared off. As in sheared off flush with the surface of the board ? If they just worked loose you are just a victim of some bad luck, hot cold related expansion and contraction Different metals, stainless, brass different properties. Elastomer adds to variables. 6 mm of engagement could result in bottoming out of screws which means they really aren't tight you just cant turn them anymore. Once you start to ride they wiggle out( back and forth) resulting in sliced knee. Check thread depth of insert. If threads are stripped in inserts I would drill them out and replace with stainless inserts. Probably not enough sidewall in brass insert to go up one thread size even 1/4 inch fine thread would leave you with little material to safely screw into. The good thing about brass inserts is you can drill them out without creating too much heat. Sharp bit, slow speed. The rear leg thrash you mention is something I have experienced once . Never want to feel that again. (Hang it up and be thankful the learning experience didn't cost you more.)That's the older experienced me second guessing the younger more inexperienced me. Good luck! Quote Link to comment Share on other sites More sharing options...
nekdut Posted February 17, 2014 Author Report Share Posted February 17, 2014 Sorry I wasn't clear. The screws came out of the inserts and did not snap off. What I am trying to determine is how much damage the threads took. Three of the four binding screws were lost to the snow, but I found a few brass shavings in the fourth one. The part that is confusing is that the inserts appear and feel solid when screwing back into the board now and I can't trust it as-is after what happened. I suppose helicoil or drill/tap are in order. Quote Link to comment Share on other sites More sharing options...
Beckmann AG Posted February 17, 2014 Report Share Posted February 17, 2014 If you found brass on the one remaining screw, the inserts should probably be 'helicoiled'. I have had good results with this product: http://www.travers.com/master-thread-repair-insert-sdottdotidot-sets?Category=UserSearch=recoil%20thread%20inserts||UserSearch=block%20id%2069794%20and%20class%20level3%20id%20298337||AttribSelect=Thread%20Size=M6X1.00 The nice thing about this insert, is that the core drill size is .250, so one can use an end mill rather than a drill bit, which leaves the bottom of the bore flat, and you don't have to drill any deeper than necessary to get full depth with the insert. I think I ground the insert tap (in the kit) from a starter to a bottoming type, again to get full thread to the bottom of the bore. What did you use for longer hardware? Perhaps the 'class of fit' was sufficiently loose such that the screws were only tight against the very crown of the thread-form? If so, this might explain why it seems you still have thread in the insert despite pulling the screws. Quote Link to comment Share on other sites More sharing options...
CMC Posted February 19, 2014 Report Share Posted February 19, 2014 Sorry in advance for the rant/vent.This was originally supposed to be a ride review of my original Madd 180, which some of you have been asking about. I've been waiting for decent coverage before trying this board out since it is pretty unique. We've had a had a terrible snowfall this year so it's taken some time. I finally got it out on Friday and the board blew my mind. It is truly a unique stick in the alpine snowboarding world. So, I used longer binding screws, checked and rechecked before riding, but my front binding completely sheared off of the board five runs into the day on Friday. I was hauling in a good heelside (lower Stump Alley for those who know, so you can get real speed there) and thankfully was able to get sliding my back quickly to avoid my rear leg/knee from getting thrashed from catching one-legged. I was able to collect myself gather up the yellow ering that popped off and get down to my car. Felt like some good bruising on my front knee and shin, but I was glad it wasn't any worse. Only after getting back to my car and unbooting, I noticed a little moistness on my knee and discovered a nice clean slice down to my kneecap. The board had a fresh PTC tune and most of you know how razor sharp that can be. My ski pants and under layer have perfectly straight and clean slices at the knee as well. I was able to drive myself to the hospital and get stitched up, with a little tendon damage underneath unfortunately. Now, I wanted to ask the group, how best to check if your binding attachment is truly sufficient? All four front screws had 3-4 turns of engagement and looked clean and tight. Is it just the fact classic Madd brass is softer and just gave way (particularly since these boards are getting upwards of 2 decades old)? The weird thing is that screwing back into the board still feels secure, but there's no way I am taking the board out as-is, after my visit to the ER. What are my options in making the inserts stronger as-is? Heli-coil? Or do I need to t-nut the thing to be sure? By the way, the classic 180 was phenomenal. I'm still thinking about it a few days later. It's surprisingly friendly, perhaps since this specific example spent a fair amount of time being thrashed on the world cup and has been softened a bit. It does not feel like the documented 22m elliptical sidecut, nor the 17.7m measured. It needs some speed, but once moving is pretty maneuverable, feeling more like a 13-16m radius VSR. One thing I felt (might be technique related) is that I did not complete full C-carves on this thing, it wanted to go down the fall line and just haul ass. I want to get back on this thing but am scared the binding issue will bite me again...... :( What were you using for bindings? After owning more original Madds than JG, MM and MB combined, I can say that I have never ripped a binding off the board while riding. Your long screws were probably not long enough. Helicoil could work, yet I've done successful operations by drilling through the base and replacing any bad brass inserts with non brass inserts. Good luck. Quote Link to comment Share on other sites More sharing options...
polaris Posted February 19, 2014 Report Share Posted February 19, 2014 Another possibility is that the screws were too long, bottomed out, and then over tightened (stripped). IMO the brass inserts are susceptible to damage if not used properly, but not failure during proper use. Quote Link to comment Share on other sites More sharing options...
Corey Posted February 19, 2014 Report Share Posted February 19, 2014 I tried to mount TD2s to an original Madd with brass inserts but the screws only engaged between 1 and 2 turns. I couldn't find longer screws so I didn't ride it. You did say you had 3-4 turns, so that should have been good. I'd find a way to put modern stainless inserts in that board. Brass just seems like a bad idea unless thread engagement is perfect. Quote Link to comment Share on other sites More sharing options...
gdboytyler Posted February 19, 2014 Report Share Posted February 19, 2014 Nekdut, glad to hear all your bones are intact. Quote Link to comment Share on other sites More sharing options...
nekdut Posted February 21, 2014 Author Report Share Posted February 21, 2014 I transplanted the exact same set of TD3s that I had on a classic Madd 170 for years over to the 180, so this is a known good set up for classic Madds. I guess the 180's brass threads were already weaker or damaged somehow. As I mentioned, first day out on that specific board, but setting it up did feel deceptively fine, and an incredible ride. I guess the helicoil option is the best bet at this point. I'll probably give Beckmann's suggestion a try. Thanks for the link Erik. Also, thanks for the concern gdboytyler. It certainly could have been much worse. Quote Link to comment Share on other sites More sharing options...
neanderthal Posted February 21, 2014 Report Share Posted February 21, 2014 I was just working on my new Nirvana and noticed that I could easily put 6 screws into each Bomber center disks because of the extra inserts on my board. Here is my question - which holes do I fill? Should I use the standard 4 holes closest to each other? (this would make it so that the screws were not centered on the center disk in my case but would be closer and may allow better flexing of the board) or do I fill the holes at the edges of the center disk so that forces are equally distributed through that disk symmetrically but the board may not flex as well, Or do I put in 6 screws so I dont have to worry about failure. My fear about 6 screws is that there would be noticeable rigidity introduced by the bindings negating the effect of the elastomer cushion do to the rigid construct of that many screws fixed to a rigid plate. Quote Link to comment Share on other sites More sharing options...
Corey Posted February 21, 2014 Report Share Posted February 21, 2014 Keep the screws at least 4 cm apart, meaning don't just use the holes closest to the center only. I typically put the screws as far apart as possible for the least leverage of the bindings on the screws, but it really doesn't matter in practice. With my m27 UPZ boots and Sidewinder bindings, some of the holes are covered by the toe and/or heel blocks so I bias the screws to whichever holes I can access. I wouldn't bother with 6 screws. That's the equivalent of sitting in the middle seat in the back of a car and fastening all 3 seat belts just because you can. Interesting, but fairly pointless. Quote Link to comment Share on other sites More sharing options...
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